Fluorescent electronic ballast
A fluorescent electronic ballast including: a rectifier circuit, for receiving an AC power supply and converting the AC power supply into a DC power supply; an inverter circuit, coupled to a fluorescent driver circuit, for converting the DC power supply into a high-frequency AC power supply for driving a fluorescent; and a detection protection circuit, coupled to the rectifier circuit and the inverter circuit, for detecting the DC power supply provided by the rectifier circuit, and cutting off the electric connection between a control chip of the inverter circuit and all of power supply when the voltage of the direct current power supply is lower than a predetermined value, wherein the power supply at least includes the direct current power supply provided by the rectifier circuit.
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This Non-provisional application claims priority under 35 U.S.C. §119(a) on Patent Application No(s). 103,100,143, filed in Taiwan, Republic of China on Jan. 3, 2014, the entire contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION1. Field of the Invention
The present invention relates to a detection protection technology for fluorescent electronic ballasts.
2. Description of the Related Art
Fluorescent lamps have excellent power saving features, and have gradually become the mainstream lamps, replacing the traditional incandescent lamp. There is a difference between the fluorescent lamp and the incandescent lamp, which is that the fluorescent lamp has to be used with electronic ballast for producing high voltage for ionizing gas in the lamp.
Therefore, the present invention provides a new fluorescent electronic ballast, which can prevent damaging power semiconductor switching units and control chip in an inverter circuit of the electronic ballast, thus prolonging the lifetime of the fluorescent lamp.
BRIEF SUMMARY OF THE INVENTIONThe present invention provides a fluorescent electronic ballast. The fluorescent electronic ballast has: a rectifier circuit, for receiving an alternating current (AC) power supply and converting the alternating current into a direct current (DC) power supply; an inverter circuit, coupled to a fluorescent driver circuit, for converting the direct current power supply into a high-frequency alternating current power supply for driving a fluorescent; and a detection protection circuit, coupled to the rectifier circuit and the inverter circuit, for detecting the direct current power supply provided by the rectifier circuit, and cutting off the electric connection between a control chip of the inverter circuit and all of power supply when the voltage of the direct current power supply is lower than a predetermined value, wherein the power supply at least comprises the direct current power supply provided by the rectifier circuit.
A detailed description is given in the following embodiments with reference to the accompanying drawings.
The present invention can be more fully understood by reading the subsequent detailed description and examples with references made to the accompanying drawings, wherein:
The following description is of the best-contemplated mode of carrying out the invention. This description is made for the purpose of illustrating the general principles of the invention and should not be taken in a limiting sense. The scope of the invention is best determined by reference to the appended claims.
The detection protection circuit 207 of the present invention at least comprises a trigger unit 272 and a control unit 274. In the embodiment of
In the embodiment of
In a preferred embodiment, as shown in
Note that, for illustration, the first and the second transistors Q1 and Q2 in the embodiments are bipolar junction transistors (BJTs), however those skilled in the art will understand that the type of transistor should not be limited thereto. For example, the first and second transistors Q1 and Q2 can be metal-oxide-semiconductor field-effect transistors (MOSFETs). In order for the overall electrical characteristics of the fluorescent electronic ballast to meet the requirements of various applications, those skilled in the art can properly design the values of the resistance and capacitance, and modify the circuit arrangement in the aforementioned embodiments based on the principle of the present invention.
While the invention has been described by way of example and in terms of the preferred embodiments, it is to be understood that the invention is not limited to the disclosed embodiments. On the contrary, it is intended to cover various modifications and similar arrangements (as would be apparent to those skilled in the art). Therefore, the scope of the appended claims should be accorded the broadest interpretation so as to encompass all such modifications and similar arrangements.
Claims
1. A fluorescent electronic ballast, comprising:
- a rectifier circuit, for receiving an alternating current (AC) and converting the alternating current into a direct current (DC) power supply;
- an inverter circuit, coupled to a fluorescent driver circuit, for converting the direct current power supply into a high-frequency alternating current power supply for driving a fluorescent; and
- a detection protection circuit, coupled to the rectifier circuit and the inverter circuit, for detecting the direct current power supply provided by the rectifier circuit, and determining whether cutting off the electric connection between a control chip of the inverter circuit and all of power supply when a voltage of the direct current power supply is lower than a predetermined value, wherein the power supply at least comprises the direct current power supply provided by the rectifier circuit, wherein the detection protection circuit comprises: a control unit, comprising a first transistor, coupled to a power supply terminal of the control chip of the inverter circuit; and a trigger unit, further comprising: a second transistor, coupled to the first transistor, wherein the first transistor is cut off as the second transistor is cut off; and a first Zener diode, having a negative terminal coupled to an output terminal of the rectifier circuit; and a positive terminal coupled to the second transistor, wherein when the voltage of the direct current power supply is lower than the predetermined value, the second transistor is cut off and the first transistor is cut off.
2. The fluorescent electronic ballast as claimed in claim 1, wherein the power supply cut by the detection protection circuit when the voltage of the direct current power supply is lower than the predetermined value further comprises a direct current power supply which is fed back to the control chip from the inverter circuit.
3. The fluorescent electronic ballast as claimed in claim 1, wherein the detection protection circuit further comprises:
- a high-voltage startup unit, coupled to the control unit of the detection protection circuit, for limiting an input voltage of the first transistor under a specific voltage level.
4. The fluorescent electronic ballast as claimed in claim 3, wherein the high-voltage startup unit further comprises:
- a second Zener diode, having a negative terminal coupled to the direct current power supply feedback from the inverter circuit, and a positive terminal coupled to a ground; and
- a capacitor, connected to the second Zener diode in parallel.
5. The fluorescent electronic ballast as claimed in claim 1, further comprising: a power factor correction circuit, coupled to the rectifier circuit, for increasing power factor of the fluorescent electronic ballast.
6. The fluorescent electronic ballast as claimed in claim 1, further comprising: a filter circuit, coupled between the rectifier circuit and a mains supply, wherein the mains supply provides the alternating current power supply, and the filter circuit is used for filtering out the high-frequency noise from the alternating current power supply.
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- Office action from corresponding Taiwanese application No. 103100143, mailed Aug. 18, 2015, 4 pages.
Type: Grant
Filed: May 29, 2014
Date of Patent: Jan 5, 2016
Patent Publication Number: 20150195889
Assignee: DELTA ELECTRONICS, INC. (Taoyuan)
Inventors: Ching-Ho Chou (Taoyuan Hsien), Yung-Chuan Lu (Taoyuan Hsien), Yen-Yu Chen (Taoyuan Hsien)
Primary Examiner: Tung X Le
Application Number: 14/290,669
International Classification: H05B 37/02 (20060101); H05B 41/282 (20060101);